Dental hand piece



April 18, 1950 STAUNT 2,504,233

DENTAL HAND PIECE Filed NOV. 28, 1947 i g2 r I I as 1 a 5 H I 3/ Ii 1 42 1 INVENTOR fzar'fim 5 l Patented Apr. 18, 1950 UNITED STATES PATENT OFFICE Martin vStaunt, Chicago, 111.

Application November 28, 1947, Serial No. 788,558

".2 Claims.

The present invention relates to dental "hand pieces, and is-part-icularly concerned with'devices or arrangements by means of which the various dental drills, burrs, sanding wheels, or other tools aresecuredin the hand piece.

One of the objects of the invention is the provision of an improved dental hand piece, which is provided with an "improved means for securing the shank of a tool in-the hand piece, in such mannerithat the shank is positively held and secured against axial movement and caused-to rotate with the driving mechanism of the handpiece.

Another object of the invention is the provision of an improved dental handpiece which is adapted to be used with standard tools which are now on the market, and which is adapted to grip them quickly and positively, and is also adapted to effect .a quick release without the difficulties "which are encountered with some of the devices of the prior art.

.A further object of the invention is the provisionof an improved dental handpiece, in which the structure is simple, capable of economical manufacture, sturdy, uniform in its operation, and adapted to be used for a long period of time without-necessity for repair or replacement of any of its parts.

Another object of the invention is the provisionofan improved dental handpiece, in which the grip Of the tool shank is automatic, and alwaysin the same manner with substantially the same pressure, and in which the shank may be instantly released, the latter being accomplished merely by pressing a resilient "member, and the former merely by releasing it and removin the pressure'of the thumb or fingers.

Another object of the invention is the provision of an improved contra-angle structure, in which all of the bearings are enclosed and adequately protected against ingress of saliva or gritty materials such as are sometimes used in polishing teeth, so that the bearing "lubrication may b maintained at all times. thus assuring a lonclif (Either objects and advantages or the invention will 'be apparent from the followingdescription andthe accompanying drawings, in which similar characters of reference indicate similar parts throughout the-several views.

Refer in to the single sheet of drawings,

Fig. lie-a fra mentary sectional view taken through thewdrlving head or contra-angle of a dental handpiece, embodringihe invention, on a '2 plane determinedhy the axes of the driving and driven shafts:

Fig. 12 is a fragmentary vertical sectional view, taken on the plane of the line 22 of Fig. '1, looking in the direction of the arrows;

Fig. 3 is a bottom plan view of an intermediate actuating member by means of which the grip.

ofthe tool shank is controlled;

Fig. 4*is a side elevational view of the intermediate actuating member of Fig. 3;

Fig. '5 is -a fragmentary side elevational view of the end of standard tool shank for dental "burrs or the like, which the present handpiece is adapted to receive'and use;

Fig. .6 "isa fragmentary sectional view taken on the plane of the'line 6--6 of Fig. 1,1ooking in the direction of thearrows; and I Fig. 7 is a fragmentary sectional view taken on the plane of the line 1-1 of Fig. 1, looking in'the direction of the arrows.

Referring to Figs. '1 and 2, Ill indicates in its entirety the driving head or contra-angle of the handpiece, which is carried bythe tubular housing Ii, having a driving shaft l2. The tubular housing ,maybe part of the standard handpiece housing itself, or it may be part of an attachmentcommonly called a contra-angle, the housing of which'is carried by the handpiece, and the shaft of which is gripped by a handplece chuck.

'The housing member ll, constitutes a'bearing for the shaft 12, 'by'means of its cylindrical bore 13, in which'the shaft I2 is mounted for rotation, and it may also be called a bearing member. Bearing member H preferably has a reduced threaded end portion [4, to be received in the threaded bore iii, of the contra-angle housing 16. An annular shoulder '17, on the bearing member ll, engages the plane end surface I8 on "the contra-angle housing It.

The shaft I2 carries a pinion l9, at its right end in Fig.1, and the pinion l9 comprises a substantially cylindrical body having an outer cylindrical -surface 20 andfhaving a cylindrical bore 2|. Pinion i9 is secured to shaft '12 by a transverse through pin 22, and pinion I9 is provided at its' ;'rlght end with axially projecting gear teeth 23.

Gear 'teeth 23 are adapted to mesh with and drive the geariteeth '24 on a driven pinion 2i which drive'sgthe tool shaft 26. "The contraangle liousi'n fit comprises a metal member hav ing two tubular portions '21 and '28.,whicl'i are at substantially right angles to each other. "The tubular *portion 28 ends in a threaded bore 28 The outside of the annular flange 36 may be formed with a concavely curved annular surface 39, and the periphery 46 of the fiange-36rmay I be noncircular for receiving a wrench. Adjacent the hub 33 the outer surface of the bearing flange 36 may be flat at 4|, but there is always a clearance between this surface and the saliva guard v so as to reduce friction at the point. 1

The hub 33 has an outer cylindrical surface 43 to be rotatably received in the bearing-bore 32, and the hub 33 is long enough to project axially from the bearing bore 32. At its outer end hub 33 has a reduced cylindrical portion 44, and an annular shoulder 45 for receiving and engaging the saliva guard 42. Saliva guard 42 comprises an annular metal member having a central bore 46 for receiving the reduced end 44. The saliva guard has a radially extending flange 41 which curves backward toward the concave surface 39, butdoes not engage thesurface as there is a clearance between them. The outer curved surface 48 of saliva guard 42 is flush with the end 49 of the bearin 33 and with the end 58 of the driven shaft 26. The radial flange 41 of the saliva guard 42 is preferably kept inside the boundaries of the bearing flange 36 so that the saliva guard does not project far enough tocome into contact with the gums or parts of the mouth of the patient, as the saliva guard 42 rotates with the shaft 36 and tool shank 5|. By virtue of the radially projecting flange 41 the saliva guard 42 tends to throw on saliva which might otherwise find its way into the bearing bore 32, but the backward curvature ofthe flange 41 directs the saliva against the curved surface 39 of the bearing flange 36. The hub 33 of pinion 25 has a cylindrical bore 52 which is adapted-to receive a tubular driven shaft 26, which may be brazed or soldered to the pinion 25. Shaft 26 comprises a cylindrical metal member which may be closed at its upper end, the upper end having an external frustoconical surface 53. At its upper end the tubular portion 28 of the housing has a threaded bore 54 for receiving the threads 55 of a cap bearing member 56.

This cap bearing member has a cylindrical bore 51 for receiving the end of the tubular shaft 26, and it has a frusto-conical surface 58 for engaging the complementary end surface 53 on the shaft26. The cap bearing member 56 is made as short as possible so that it does not project far from the housing portion 28, and it may have an external noncircular portion59 for engagement with a wrench.

The tubular shaft 25 has an internal cylindrical bore 68 of sufficient size to receive thecylin drical tool shank 5|, but at its upper end the bore 60 has an inwardly-projecting portion with a flat surface 6|. This flat surface 6| is adapted to engage the fiat surface 62 on the end portion of every tool shank 5|,-as shown in Fig. 5. The standard tool shank has agroovej63 extendin about its periphery near to itsupper: end 64. the

groove 63 terminating at the flat surface 62. The groove 63 is preferably rectangular in crosssection, the bottom 65 of the groove being a. cylindrical surface. The engagement between the fiat surfaces 62 on the shank 5| and 6| in the shaft bore 69 holds the shank against rotation with respect to the shaft.

The end surface 66 of the cylindrical portion of the shank at the flat surface 62 may be slightly undercut. Shaft 26 also haso'ne or more through bores 61 of suiiicient size to receive a steel ball 68, and each end of the through bore 61 is slightly spun over so that the ball 68 is retained in vthebore 61 and does not drop out when the shank 5| is removed.

The diameter of the ball 68 is greater than the thickness of the tubular shaft wall 26, so that the ball 68 may project into the groove 65 of the tool shank 5| when the parts are in the position of Fig. 1. The shaft 26 is surrounded by a ball actuating member 69 comprising a tube having a frusto-conical flange-10 at its upper end. i

The tube 69 may be engaged by a helicalcoil spring at its lower end or the coil spring 1| may be formed as an integral part of the tube 69. At its lower end the spring 1| reacts against an annular surface 12 on driven pinion 25 inside the teeth 24. At its upper end the inner frustoconical surface 13 engages the ball 68 and cams it inward in the bore 61 into the groove 65 of the tool shank 5|. Spring 1| constantly urges the ball into position to engage in groove 65'of tool shank 5| whereby the tool shank 5| is held in the tubular shaft 26.

In order tov release the tool shank 5|. from the shaft 26 the chamber 14 in the tubular portion 28 contains an intermediate actuating member 15 in th'e fo'rm of a fiat spring, as shown in Fig. 3. This intermediate actuating member has a central bore 16 for clearing the outer cylindrical surface of shaft 26, and it may havean outer circular boundary 11. At one side the circular boundary 11 has a radial extension 18 which is turned downwardly at 19 to bear against the base of a groove 8| in the tubular portion 21.

The extension 18 then extends horizontally in Fig. 1, and has an attaching flange 8 2 which is secured to the base 80 of groove 8| by a screw bolt 83. Thus intermediate actuating member 15 is firmly supported at its left end, and it maybe so shaped that itis urged upward against the inside of the top of tubular housing 28 out of engagement with the end of the tubular mem: ber 69. I l

The member 15 preferably has a pair of V;- shaped knife-edged ridges84 on its lower 'side. These engage the upper fiat end of thetubular. member 69 when the spring 15 is pushed downward, but ordinarily the ridges 84 do not engage. the end of the tube 69 becausethe tube 69 stops short of the ridges 84 when it urges ball 68 into final position in groove 65. This' clearanc'e between ridges 84 and end 85 of tubular member 69 prevents running friction at this point. 7

The groove 8| may be a rectangular sl'otin the upper wall'of the tubular portion'21, and it is adapted to receive a manual actuating member 86, which is pivotally mounted upon a through pin 81 carried bytubular portion 21. In order to house the lever 86 tubular portion21 may have a pair of upwardly projecting ribs or flanges 88, one on each-side of the groove 8|.

The manual actuating member 86 comprises a substantiallyrectangular lever with a rounded upper thumb etllifaqe 53,9 apda downward turned.

end 90 that engages the spring 15 at a point in- 'dicated-in Fig. 3 at 9|. Manual actuating member 86 projects from groove 81 enough to be engaged by :Ithe thumb at *its extreme e On the side hi th downwardly projecting po ion 911 on which-there may be a projecting lip 9|,and .the end of'the groove 8! may have a shoulder 92 overhanging the lip 9| so that lever 86 is l'mlited its upward motion, and cannot swing out of slot 8|. Lip 9| is inserted beneath shoulder 92 before the pin 31 is driven into its friction bore.

The operation of my h-andpiece for holding tool shanks is as follows: When a tool shank 5| is to be inserted in the bore 60 of shaft 26 the thumbpiece 8'6 may be pressed until intermediate actuating member 15 brings its knife edges 84 into engagement with the end of tubular member 69.

Tubular member 69 may then be pressed downward compressing the spring H and permitting the ball 68 to move radially outward until the cylindrical end of tool shank 5| can pass the ball 68. The tool shank must be turned until the fiat surface 62 registers with the flat surface 6| in the bore fill, and then the shank may be inserted to the position of Fig. 1.

Upon relieving pressure on the thumbpiece 86 spring 15 will lift its knife edges 84 from the end of tube 69, and the frusto-conical inner surface 13 will cam the ball 68 radially inward until it is seated in the groove 65, holding the tool shank in the tubular shaft 26.

When the tool shank Si is to be released, it is only necessary to press upon the thumbpiece 86 which engages actuating member 15 which drives tubular member 69 downward permitting ball 68 to be cammed out of slot 65 as the shank 5| is withdrawn.

It will thus be observed that I have invented an improved structure for dental handpieces, by means of which a dental tool, such as a burr or drill may be inserted and secured automatically in the drive shaft of the contra-angle. All that is needed is to insert the tool shank while twirling it slightly between the fingers, and at the same time to press upon the thumb piece 86, momentarily, and the latter being released while the shank is in its final position, the shank is firmly secured in the shaft.

The present invention may be used with standard tool shanks now on the market, and it is a simple matter to remove the tool, as it is only necessary to press the thumb piece 86, and then simultaneously pull on the tool. With the present invention the tool shank does not protrude from the top of the contra-angle, but is fully enclosed. The bearings of the present device are also protected against entrance of saliva or grit, and the device may be used for a long period of time without necessity for repair or replacement of any of its parts.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do 'not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a contra-angle for dental hand pieces, the combination of a housing .having a pair of tubular portions extending transversely to each othenwithabearingthreadedly mounted in each of said tubular portions, a drive shaft having a gear in one of saidtubular portions and a driven gear in the other-of, said tubular portions, said driven :gear having a cylindrical hub projecting from its bearing, a rotatable saliva guard fixedly secured to said hub and rotating with the 'hu'b, said guard being arranged flush with the outer end of the hub, and having a backwardly'turned substantially conical portion overlying the end of the adjacent bearing, a tubular shaft located in said hub and extending upwardly, and pro vided with a-second threaded bearing carried by said "housing at 'its' other end, the said shaft having a cylindrical bore terminating at said other "end in a partially cylindrical portion having a flatted side wall for engagement with a standard shank of a dental tool, a tubular resilient metal member surrounding said tubular shaft above the driven gear, said resilient member having one tubular end engaging the hub of the driven gear and being formed with a plurality of integral helical spring portions integrally joined to another tubular portion, said latter tubular portion having a bell shaped frusto-conical end portion, said tubular shaft being provided with a plurality of regularly spaced apertures located in the same plane, which is transverse to the axis of the shaft, and said apertures each being provided with a ball for engaging in a groove in the dental tool shank, the said bell shaped portion urging the balls inwardly into said groove, and means carried by the contraangle for com-pressing said resilient member and moving the bell shaped portion longitudinally away from the balls to permit the balls to move out of the groove to release the shank of the dental tool.

2. In a contra-angle for dental hand pieces, the combination of a housing having a pair of tubular portions extending transversely to each other, with a bearing threadedly mounted in each of said tubular portions, a drive shaft having a gear in one of said tubular portions and a driven gear in the other of said tubular portions, said driven gear having a cylindrical hub projecting from its bearing, a rotatable saliva guard fixedly secured to said hub and rotating with the hub, said guard being arranged flush with the outer end of the hub, and having a backwardly turned substantially conical portion overlying the end of the adjacent bearing, a tubular shaft located in said hub and extending upwardly, and provided with a second threaded bearing carried by said housing at its other end, the said shaft having a cylindrical bore terminating at said other end in a partially cylindrical portion having a flatted side wall for engagement with a standard shank of a dental tool, a tubular resilient metal member surrounding said tubular shaft above the driven gear, said resilient member having one tubular end engaging the hub of the driven gear and being formed with a plurality of integral helical spring portions integrally joined to another tubular portion, said latter tubular portion having a bell shaped frusto-com'cal end portion, said tubular shaft being provided with a plurality of regularly spaced apertures located in the same plane, which is transverse to the axis of the shaft, and said apertures each being provided with a ball for engaging in a groove in the dental tool shank, the said bell shaped portion urging the balls inwardly into said groove, and means carried by the'contra-angle for compressing said resilient member and moving the bell arms provided with downwardly turned knife 10 edges for engaging diametric points on the bell shaped portion of the resilient member, so that a pressure on the pivoted lever urges theleaf spring downward and compresses the resilient member to release a tool shank.

. MARTIN STAUNT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number I Name Date 1,465,690 Smith Aug. 21, 1923 1,638,175 Terry Aug. 9, 1927 1,853,089 Skinner Apr. 12, 1932 2,010,210 Witt Aug. 6, 1935 

